Electric typewriter



March 10, 1953 D. MASTlNl 2,630,899

ELECTRIC TYPEWRITER Filed Feb. 25, 1948 2 SHEETS-SHEET l March 10, 1953 D. MASTINI 2,630,899

ELECTRIC TYPEWRITER Filed Feb. 25, 1948 2 SHEETS-SHEET 2 Patented Mar. 10, 1953 ELECTRIC TYPEWRITER Domenico Mastini, Milan, Italy Application February 25, 1948, Serial 'No. 10,789 In Italy November '9 1945 Section El, Public Law 690, August 8., 1946 Patent expires November 9, 1965 4 Claims. (01. 197-12) It is well known that ordinary typewriters now in use essentially comprise a great number of mechanical elements which are delicate, requiring extremely precise manufacturing techniques resulting in high production costs.

Furthermore, the lever movements used in these mechanical typewriters limit the writing speed of the machine and fatigue the operator because of the mechanical effort he is required to exert with the fingers, especially when making extra copies.

In order to reduce the efiort required in typing, electric typewriters have been produced, but in addition to having the usual mechanical complications these typewriters have introduced e1ectrical elements which add to the complexity of the machine so that manufacturing costs have been noticeably increased.

The present invention, on the contrary, relates to a typewriter of simpler construction and lower cost, requiring less mechanical effort, and adapted to provide an adjustable force of typing action which may be varied according to the number of copies to be made at one time.

It is an object of this invention to provide an electric typewriter which has a minimum number of electrical connections to the type selecting mechanism, there being only three, whereas in the case of prior machines of this kind very complex circuits have been employed.

Another object of the invention is to provide a typewriter having reduced weight and small size so as to permit easier handling and transport.

.Referring now to the annexed drawings:

Figure 1 shows a transverse cross-section of an electric typewriteraccording to the invention;

Figure 2 is a plan view of the device shown in Figure 1; and

Figure 3 is a diagrammatic illustration of the wiring of the electric typewriter.

Referring now to the drawing in detail, a typeholding wheel, provided on its circular face with a plurality of indicia characters, is indicated by reference numeral i, while an electric current transmitter means 2 is adapted. in cooperation with a receiver means 3, to angularly displace the type-wheel I so as to bring the desired letters or figures selectively into position for printing impressions to be made on a paper sheet which may be carried by the roll 4. For this purpose the coil 30, annularly disposed on the type-wheel, receives currents transmitted by the transmitter 2 which create resulting magnetic fields which coconnected to contacts b4 and c4.

operate with a local magnetic field induced by current flowing in coils 2 2 and 23,, so as to ID- tarte the coil 30 together with the type-holding wheel on which it is supported.

An electromagnet 5 is adapted to move the roll 4., through the operating levers 6, in a forward direction to eifect the printing of the type impressions on a sheet. Electric switches I are disposed so as to be closed by downward pressure exerted on the movable .keys 8. Another eleotromagnet 9 provides .for the printing of capital letters, these letters being arranged in .a lower position I13 on the type-holding wheel I. The upward shifting of the type-holding wheel, which is pivotally supported by a pin I0, is accomplished by energizing the electromagnet 9. To return the type-holding wheel I from the capital letter position to the small letter position, an electromagnet ll disengages a locking pawl (not shown) in order to permit the typeholding wheel to drop to its lower position by gravity.

A rotatable contactor device l2, which turns with the coil 30 and the type-holding wheel I, is provided with a plurality of contacts, '29., l zb, We, etc., corresponding to the number of type character positions of the type-holding wheel. These movable contacts will selectively make a connection through the stationary contact [2' to energize the electromagnet 5, after the coil 30 has reached a position determined by the actuation of any one of the keys 8. A centering tooth l5 properly positions the type-holding wheel when the roll 4 is moved forward for each printing impression. The usual ribbon holders are indicated at M.

The transmitter means 2 comprises a resistance H, which is connected at diametrically opposite points I8 and I9 to the positive and negative poles, respectively, of a direct current source I16 which may be a rectifier, which may be connected to the usual utility outlet. The leads 2!] and 2] are connected to the field magnets 22 and 23 of the receiver 3. The resistance I1 is provided with a number of sets of taps (only three sets of which are shown) corresponding to the number of type controlling keys 3 on the typewriter keyboard. The three taps for each of the keys 8, as for example the taps a1, a2 and as leading to the contacts or, are displaced from each other on the resistance ll. Similarly, the tape b1, b2, b3 and taps c1, c2, 03 are respectively When one of the keys 8 is depressed, it actuates the appropriate switch 1 to connect a set of three taps from 3 resistance 11 to the leads 24, 25 and 26 to feed the coil 30 of the receiver '3. Since for each position of the sets of taps voltages of different value and direction will exist between the individual taps in the set there will be applied different voltages to the coil 30which will cause different current flows in the sections 21, 2'8 and 29 of the coil. These currents, flowing simultaneously through the difierent sections of the coil will generate a resulting magnetic field having a characteristically different pattern for each of the sets of taps on the resistance [1, and hence for each of the keys 8. Mutual action of the magnetic field of the coil 30 with the magnetic field of the coils 22 and 23 causes a rotary motion of the coil 30 together with the type-holding wheel I on which it is supported until it reaches the position, determined by the particular key 8 which has been operated, in which the magnetic forces are in equilibrium.

In other words, for each key 8 there is a corresponding magnetic flux pattern generated in the coil 30 which will be in equilibrium with the magnetic flux generated by the coils 22 and 23 at a given angular position of the type-holding Wheel 1; hence, for each key there is a corresponding type character which will be brought into printing position.

This rotative movement also brings into position the corresponding contact element of the contactor 12 which has as many contacts as there are indicia characters on the type-holding wheel. When one of the keys 8 is depressed, the respective contacts associated with the appropriate switch I are closed and the type-holding wheel i rotates with the contactor i 2. When the latter is brought to rest the corresponding one of the contacts [2a, [2b, I20, etc. will close the circuit through contact I2 which energizes the electromagnet 5 to cause a printing impression to be made by forward movement of the roll 4. When the pressure on the key 8 is released the roll 4 will return backwardly and the mechanism will come to rest. The type-holding wheel will remain in the same position until another key sets it in motion to select another type character and cause a printing operation. There has also been provided a variable resistor means 3: which is connected in the circuit with the electromagnet 5 and serves to regulate the current intensity flowing through it in order to control the force with which the printing impression of the roll on the type-holding wheel is made, the strength of said impression being proportional to the number of copies to be made.

In the example of the invention described and illustrated there have been omitted some of the elements adapted to actuate various other devices necessary in the operation of the typewriter as a whole, such as the forward and return movements of the carriage, the rotation of the roll, the spacing, eto., since these mechanisms are well known to those skilled in the art.

Furthermore, the embodiment of the invention shown and described here is given only as an example, as in practice the arrangement of the various elements may differ somewhat, provided that the inventive idea is utilized. And obviously, there will be additional circuits for generating difierently oriented magnetic fields in the coil 30 corresponding to additional keys provided on the keyboard of the typewriter.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In an electrically operated typewriter having a movable type-wheel, a ring shaped rotor coil on the type-wheel, a pair of fixed stator coils arranged diametrically with respect to the rotor coil, a plurality of conductors for creating a flux pattern in the rotor coil, means for energizing the stator coils so that interacting magnetic forces are set up between the stator coils and the rotor coil which will be in equilibrium in only one position of the rotor coil, and switching means for altering the electrical potential in all of said conductors for angularly shifting the flux pattern in the rotor coil, all of said conductors being utilized for each position of said flux pattern.

2. In an electrically operated typewriter having an angularly displaceable type-wheel carrying a plurality of indicia, flux-responsive means to move the type-wheel, flux-producing means, manually operable switching means including a keyboard, a roll, electromagnetic means to make an impression of an indicium on said roll, a plurality of conductors connecting said switching means and said flux-producing means, means including said switching means to establish individual characteristic electrical potentials in all of said conductors to shift the flux pattern of said fluxproducing means when an individual key of said keyboard is actuated and thereby select an indicium to be impressed on said roll, and electrical circuit means for energizing said electromagnetic means to make the impression when said indicium has been selected.

3. A device as claimed in claim 2, in which the electrical circuit means for energizing the electromagnetic means includes a plurality of electrical contacts circularly disposed on the typewheel corresponding to said indicia.

4. In a typewriter having electrically operated indicia selecting means and electrically operated impression making means, a manually operated switching means, a plurality of conductors connecting the switching means and the indicia selecting means, circuits for the switching means to establish individual characteristic electrical potentials in all of said conductors to select an individual indicium to be impressed, all of said conductors being utilized to make each said selection, and second switching means responsive to selection of an indicium to actuate said impression making means.

DOMENICO MAS'IINI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,097,789 Cahill May 26, 1914 1,187,784 Rawls June 20, 1916 2,093,545 Bryce et al Sept. 21, 1937 2,130,229 Close et al. Sept. 13, 1938 FOREIGN PATENTS Number Country Date 283,501 Italy of 1931 

